This adds a few functions to fill a struct got_object_id from specific
fields of a got fileindex entry.  In worktree.c we have a few calls
like

	struct got_object_id id;
	memcpy(id.sha1, ie->blob_sha1, SHA1_DIGEST_LENGTH);

that will break when the struct got_object_id will grow more fields.
The hardcoded hash size is not a problem for the moment, will still
take a while to reach the point of checking out worktrees from sha256
repos.

The proposed got_fileindex_entry_get_*_id set of functions will
instead first zero the id, and as not planned consequence leads to
slightly shorted code in worktree.c (albeit the loooong function
names.)

ok?

diff /home/op/w/got
commit - 188f8dcf2c1c15bf37859e3b587bc6331fd5a097
path + /home/op/w/got
blob - 6d94e2ef4017332aaa8d60289a09e393f1dbbd99
file + lib/fileindex.c
--- lib/fileindex.c
+++ lib/fileindex.c
@@ -1230,4 +1230,31 @@ RB_GENERATE(got_fileindex_tree, got_fileindex_entry, e
 	return err;
 }
 
+struct got_object_id *
+got_fileindex_entry_get_staged_blob_id(struct got_object_id *id,
+    struct got_fileindex_entry *ie)
+{
+	memset(id, 0, sizeof(*id));
+	memcpy(id->sha1, ie->staged_blob_sha1, sizeof(ie->staged_blob_sha1));
+	return id;
+}
+
+struct got_object_id *
+got_fileindex_entry_get_blob_id(struct got_object_id *id,
+    struct got_fileindex_entry *ie)
+{
+	memset(id, 0, sizeof(*id));
+	memcpy(id->sha1, ie->blob_sha1, sizeof(ie->blob_sha1));
+	return id;
+}
+
+struct got_object_id *
+got_fileindex_entry_get_commit_id(struct got_object_id *id,
+    struct got_fileindex_entry *ie)
+{
+	memset(id, 0, sizeof(*id));
+	memcpy(id->sha1, ie->commit_sha1, sizeof(ie->commit_sha1));
+	return id;
+}
+
 RB_GENERATE(got_fileindex_tree, got_fileindex_entry, entry, got_fileindex_cmp);
blob - 0c22385de5665de7e4366e6db2b42d3737058e0f
file + lib/got_lib_fileindex.h
--- lib/got_lib_fileindex.h
+++ lib/got_lib_fileindex.h
@@ -174,3 +174,14 @@ void got_fileindex_entry_mark_deleted_from_disk(struct
 int got_fileindex_entry_staged_filetype_get(struct got_fileindex_entry *);
 
 void got_fileindex_entry_mark_deleted_from_disk(struct got_fileindex_entry *);
+
+/*
+ * Retrieve staged, blob or commit id from a fileindex entry, and return
+ * the given object id.
+ */
+struct got_object_id *got_fileindex_entry_get_staged_blob_id(
+    struct got_object_id *, struct got_fileindex_entry *);
+struct got_object_id *got_fileindex_entry_get_blob_id(struct got_object_id *,
+    struct got_fileindex_entry *);
+struct got_object_id *got_fileindex_entry_get_commit_id(struct got_object_id *,
+    struct got_fileindex_entry *);
blob - 68a09786e6a0e800e79ea54e221f936dea9da837
file + lib/worktree.c
--- lib/worktree.c
+++ lib/worktree.c
@@ -1717,9 +1717,9 @@ get_file_status(unsigned char *status, struct stat *sb
 
 	if (staged_status == GOT_STATUS_MODIFY ||
 	    staged_status == GOT_STATUS_ADD)
-		memcpy(id.sha1, ie->staged_blob_sha1, sizeof(id.sha1));
+		got_fileindex_entry_get_staged_blob_id(&id, ie);
 	else
-		memcpy(id.sha1, ie->blob_sha1, sizeof(id.sha1));
+		got_fileindex_entry_get_blob_id(&id, ie);
 
 	fd1 = got_opentempfd();
 	if (fd1 == -1) {
@@ -1929,7 +1929,7 @@ update_blob(struct got_worktree *worktree,
 				goto done;
 			}
 			struct got_object_id id2;
-			memcpy(id2.sha1, ie->blob_sha1, SHA1_DIGEST_LENGTH);
+			got_fileindex_entry_get_blob_id(&id2, ie);
 			err = got_object_open_as_blob(&blob2, repo, &id2, 8192,
 			    fd2);
 			if (err)
@@ -3343,19 +3343,14 @@ report_file_status(struct got_fileindex_entry *ie, con
 	    staged_status == GOT_STATUS_NO_CHANGE && !report_unchanged)
 		return NULL;
 
-	if (got_fileindex_entry_has_blob(ie)) {
-		memcpy(blob_id.sha1, ie->blob_sha1, SHA1_DIGEST_LENGTH);
-		blob_idp = &blob_id;
-	}
-	if (got_fileindex_entry_has_commit(ie)) {
-		memcpy(commit_id.sha1, ie->commit_sha1, SHA1_DIGEST_LENGTH);
-		commit_idp = &commit_id;
-	}
+	if (got_fileindex_entry_has_blob(ie))
+		blob_idp = got_fileindex_entry_get_blob_id(&blob_id, ie);
+	if (got_fileindex_entry_has_commit(ie))
+		commit_idp = got_fileindex_entry_get_commit_id(&commit_id, ie);
 	if (staged_status == GOT_STATUS_ADD ||
 	    staged_status == GOT_STATUS_MODIFY) {
-		memcpy(staged_blob_id.sha1, ie->staged_blob_sha1,
-		    SHA1_DIGEST_LENGTH);
-		staged_blob_idp = &staged_blob_id;
+		staged_blob_idp = got_fileindex_entry_get_staged_blob_id(
+		    &staged_blob_id, ie);
 	}
 
 	return (*status_cb)(status_arg, status, staged_status,
@@ -3407,8 +3402,8 @@ status_old(void *arg, struct got_fileindex_entry *ie, 
 	if (!got_path_is_child(ie->path, a->status_path, a->status_path_len))
 		return NULL;
 
-	memcpy(blob_id.sha1, ie->blob_sha1, SHA1_DIGEST_LENGTH);
-	memcpy(commit_id.sha1, ie->commit_sha1, SHA1_DIGEST_LENGTH);
+	got_fileindex_entry_get_blob_id(&blob_id, ie);
+	got_fileindex_entry_get_commit_id(&commit_id, ie);
 	if (got_fileindex_entry_has_file_on_disk(ie))
 		status = GOT_STATUS_MISSING;
 	else
@@ -4782,12 +4777,10 @@ revert_file(void *arg, unsigned char status, unsigned 
 	case GOT_STATUS_MISSING: {
 		struct got_object_id id;
 		if (staged_status == GOT_STATUS_ADD ||
-		    staged_status == GOT_STATUS_MODIFY) {
-			memcpy(id.sha1, ie->staged_blob_sha1,
-			    SHA1_DIGEST_LENGTH);
-		} else
-			memcpy(id.sha1, ie->blob_sha1,
-			    SHA1_DIGEST_LENGTH);
+		    staged_status == GOT_STATUS_MODIFY)
+			got_fileindex_entry_get_staged_blob_id(&id, ie);
+		else
+			got_fileindex_entry_get_blob_id(&id, ie);
 		fd = got_opentempfd();
 		if (fd == -1) {
 			err = got_error_from_errno("got_opentempfd");
@@ -8282,9 +8275,8 @@ check_stage_ok(void *arg, unsigned char status,
 		return got_error_from_errno("asprintf");
 
 	if (got_fileindex_entry_has_commit(ie)) {
-		memcpy(base_commit_id.sha1, ie->commit_sha1,
-		    SHA1_DIGEST_LENGTH);
-		base_commit_idp = &base_commit_id;
+		base_commit_idp = got_fileindex_entry_get_commit_id(
+		    &base_commit_id, ie);
 	}
 
 	if (status == GOT_STATUS_CONFLICT) {
@@ -9116,22 +9108,17 @@ report_file_info(void *arg, struct got_fileindex_entry
 	if (pe == NULL) /* not found */
 		return NULL;
 
-	if (got_fileindex_entry_has_blob(ie)) {
-		memcpy(blob_id.sha1, ie->blob_sha1, SHA1_DIGEST_LENGTH);
-		blob_idp = &blob_id;
-	}
+	if (got_fileindex_entry_has_blob(ie))
+		blob_idp = got_fileindex_entry_get_blob_id(&blob_id, ie);
 	stage = got_fileindex_entry_stage_get(ie);
 	if (stage == GOT_FILEIDX_STAGE_MODIFY ||
 	    stage == GOT_FILEIDX_STAGE_ADD) {
-		memcpy(staged_blob_id.sha1, ie->staged_blob_sha1,
-		    SHA1_DIGEST_LENGTH);
-		staged_blob_idp = &staged_blob_id;
+		staged_blob_idp = got_fileindex_entry_get_staged_blob_id(
+		    &staged_blob_id, ie);
 	}
 
-	if (got_fileindex_entry_has_commit(ie)) {
-		memcpy(commit_id.sha1, ie->commit_sha1, SHA1_DIGEST_LENGTH);
-		commit_idp = &commit_id;
-	}
+	if (got_fileindex_entry_has_commit(ie))
+		commit_idp = got_fileindex_entry_get_commit_id(&commit_id, ie);
 
 	return a->info_cb(a->info_arg, ie->path, got_fileindex_perms_to_st(ie),
 	    (time_t)ie->mtime_sec, blob_idp, staged_blob_idp, commit_idp);